Question

How do you solve by substitution `4x-7y=10` and `y= x-7`?

Answer 1

Given
[1]`color(white)("XXXX")` `4x-7y = 10`
[2]`color(white)("XXXX")` `y = x-7`

Using [2] substitute `(x-7)` for `y` in [1]
[3]`color(white)("XXXX")` `4x - 7(x-7) = 10`

Simplifying
[4]`color(white)("XXXX")` `-3x +49 = 10`
[5]`color(white)("XXXX")` `x = 13`

Using [5] substitute `(13)` for `y` in [2]
[6]`color(white)("XXXX")` `y = (13) -7`
[7]`color(white)("XXXX")` `y= 6`

`(x,y)=(13,6)`